1. Field of the Invention
The present invention relates to producing a three-dimensional (3D) structural sketch (3DSS), and more specifically, to an apparatus and method of producing a 3DSS, which make it easy to produce a 3DSS from a two-dimensional structural sketch and update the produced 3DSS, and a computer-readable recording medium on which a computer program for executing the method is recorded.
2. Description of the Related Art
The development of a three-dimensional (3D) graphics technology and the expansion of the scope of related industries have increased the need for producing 3D graphics contents more quickly and precisely.
FIG. 1 is a block diagram of a conventional apparatus for producing 3D graphics contents. FIG. 2 illustrates examples of query items. FIG. 3 illustrates examples of models retrieved by the conventional apparatus of FIG. 1 after receiving a query item illustrated in FIG. 2.
Referring to FIGS. 1 through 3, the conventional apparatus for producing 3D graphics contents includes a query item input unit 100, a model-producing unit 110, and a model-storing unit 120. OUT1 indicates 3D graphics contents produced by the model-producing unit 110.
The query item input unit 100 receives a query item and transmits the query item to the model-producing unit 110. A query item, i.e., a query object, denotes predetermined graphics contents that a user desires to produce.
The model-storing unit 120 stores a plurality of 3D-shape models that can match a predetermined query item. From the 3D-shape models stored in the model-storing unit 120, the model-producing unit 110 retrieves and outputs one or more 3D-shape models within a predetermined degree of similarity with the predetermined query item.
Query items that can be input to the query item input unit 100 include a sketch query, a text query, and a sample query. More specifically, the sketch query may include a two-dimensional (2D) contour sketch, a 3D-shape sketch, and a 2D structural sketch. The sample query may include a 2D image sample and a 3D shape sample. Reference numerals 210, 220, 230, 240, and 250 indicate a sample query, a 2D-contour sketch, a text query, a 3D-shape sketch, and a 2D-structural sketch, respectively. All of the query items illustrated in FIG. 2 indicate a bird or an airplane. Accordingly, the model-producing unit 110 produces a plurality of bird models or a plurality of airplane models as illustrated in FIG. 3.
The query items that can be used by the conventional apparatus for producing 3D graphics contents have the following problems. For example, the text query 230 can be easily produced. However, when the text query 230 is used as a query item, graphics contents, which are hard to express in words, cannot be exactly expressed. Also, the same graphics contents can be expressed differently according to people. It is not easy to produce the sketch query 220, 240 or 250, and the sample query 210 may be unavailable as a query item.
FIG. 4 is an example for illustrating limitations of a Shape3D in distinguishing shapes. More specifically, (a) of FIG. 4 indicates an “android” model and (b) of FIG. 4 indicates a shape spectrum of the “android” model described by the Shape3D. (c) and (d) of FIG. 4 indicates a shape and a shape spectrum of a “crocodile” model described by the Shape 3D.
The Shape3D is a description method of 3D shapes, which was suggested by a conventional Moving Picture Experts Group-7 (MPEG-7) and adopted as an international standard for searching the model-storing unit 120. However, the performance of the Shape3D to distinguish shapes is poor. Referring to (a) through (d) of FIG. 4, the “adroid” model and the “crocodile” model illustrated in (a) and (c) of FIG. 4 are obviously different but their shape spectrums illustrated in (b) and (d) of FIG. 4 are very similar. Consequently, the Shape3D cannot produce a proper query item.